The present invention relates to conveyers for bulk material such as granular material.
This conveyor of the invention is of the type which includes an elongated channel having a rotary transport screw disposed therein, a suitable drive being connected to the screw for rotating the same and the channel being covered by a cover. The granular material, such as grain, enters into the channel through a suitable inlet aperture while at least one outlet aperture is provided through which the granular material can be discharged. The rotary screw is supported by one or more bearings situated in the channel between the opposed ends of the rotary screw, and the support of this screw is such that it does not contact the channel.
Screw conveyors of the above type have been conventionally used in order to transport grain or other granular materials generally along a horizontal path. The distance through which the grain or other granular material is transported by such conveyors is usually on the order of 5-10 meters, and the transporting capacity is on the order of several tons per hour. It is of course possible to construct longer screw conveyors, so that the transporting distance may be on the ordrer of 20-30 meters, and in principle it is possible to construct even longer conveyors. Such screw conveyers are also known to have a relatively high transporting capacity.
With conventional screw conveyers of the above type there is generally a channel of substantially of U-shaped cross section supporting within itself the rotary conveyer screw. The channel generally has a removable cover. The conveyer screw is supported in the channel by bearings situated at suitable locations along the conveyer screw, the support of the latter being such that it does not contact the channel itself. The material is usually introduced into the conveyer through an aperture at the top of the conveyer, while discharge of the material usually takes place at an end of the conveyer, although it is also possible to discharge material from a location situated at an intermediate part of the conveyor. Often the screw conveyer is relatively long, and in this case it is possible to provide discharge at any one of a number of different points along the conveyer, generally at one point at a time. For this purpose one or more discharge apertures are provided along the conveyer usually at the bottom or side of the channel, and such discharge apertures may be selectively opened by a suitable closure flap provided for each such aperture. Thus when the latter flap is closed the material will be conveyed to the end of the conveyer while when a selected flap is opened the material will be discharged through an aperture situated in advance of the end of the conveyer.
With conventional screw conveyer attempts have been made to make the bearings of the conveyer screw as small as possible so that these bearings will not interfere with the passage of the material past the bearings. Moreover, in order that the material will reliably fall by gravity through a discharge aperture situated in advance of the end of the conveyer, it is essential to make such an aperture of a sufficiently great length, and, in addition, the speed of rotation of the conveyer screw should be small enough so that the material which is transported, or at least part of it, will not be transported along with the conveyer screw beyond the aperture through which it is desired to discharge the material. As a result of structural limitations of the above type encountered in conventional screw conveyers, these conveyers have a relatively low capacity, a relatively large size, and involve high costs. Because of the low speed of rotation, the transported material will remain as a residue at the bottom of the channel after the transporting operations are completed. It is therefore not possible with conventional conveyers to change rapidly from one conveyed material to another conveyed material inasmuch as the residual material at the bottom of the channel must first be removed in some way before a different material is handled by the conveyer.